It's almost the time of year again for weight-loss brands to make hay while the sun shines. And Jenny Craig is stepping up in a big way.

The leading diet brand is overhauling its approach for the post-holidays weight-loss season, adopting a new, more holistic positioning that goes beyond simple dieting. The brand has begun a relationship with the American Heart Association, supporting local efforts and reaching out to moms over their concerns about childhood obesity.

Jenny Craig has dropped its surname, to go with just "Jenny," and has recruited a slimmed-down Mariah Carey to serve as Jenny's brand icon and celebrity spokesperson.

"'Jenny' has a greater vision," CEO Dana Fiser told brandchannel. "We can do good work. Overweight is, of course, a huge part of the population. And we're concerned about children. We really think with this new brand platform and the American Heart Association that we can help modify behaviors with mothers and also influence the behaviors of children."

Jenny is changing some creative conventions, too: Rather than present a typical before-and-after contrast, Jenny decided only to show the "after" Carey, who gave birth to twins in April and credits her 70-pound weight loss to Jenny. (The "before" Carey, of course, is burned into everyone's retinas anyway.)

"It was important to see her coming out looking absolutely incredible," Fiser said. "This is a huge strategic shift in our branding and advertising campaign. Not the process of the [weight-loss] journey, but bringing her out and having her messages be more about higher-minded causes." Jenny plans a new focus on community-boosting work at its 600 U.S. locations.

With a slimmed down brand identity and a new "Jenny" in Carey (the brand's previous star clients include Carrie Fisher, Valerie Bertinelli, Nicole Sullivan and Sara Rue), the brand has stolen a march on competitors in the fourth-quarter weight-loss derby following seasonal overeating. But no doubt this competition has only begun.